Hochschule für Technik und Umwelt FHNW
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Publikation Summertime NOy speciation at the Jungfraujoch, 3580 m above sea level, Switzerland(Wiley, 16.03.2000) Zellweger, Christoph; Ammann, Markus; Buchmann, Brigitte; Hofer, Patrick; Lugauer, Matthias; Rüttimann, Ralph; Streit, Niklaus; Weingartner, Ernest; Baltensperger, UrsDuring summer 1997, speciated reactive nitrogen (NO, NO2, peroxyacetyl nitrate (PAN), HNO3, and particulate nitrate) was measured in conjunction with total reactive nitrogen (NOy) at the high-alpine research station Jungfraujoch (JFJ), 3580 m above sea level (asl). The individually measured NOy components averaged to 82% of total NOy. PAN was the most abundant reactive nitrogen compound and composed on average 36% of NOy, followed by NOx, (22%), particulate nitrate (17%), and HNO3 (7%). The NOx/NOy ratio averaged 0.25, but significantly lower values (0.15–0.20) were observed in the presence of high NOy mixing ratios. A classification of the data by synoptic weather conditions indicated that thermally driven vertical transport has a strong impact on the mixing ratios measured at the JFJ during summer. A strong diurnal cycle with maximum mixing ratios in the late afternoon was observed for convective days with north-westerly advection at 500 hPa. In contrast, during a period of convective days with a wind speed below 7.5 m/s at 500 hPa, no obvious diurnal cycle was observed. Under these meteorological conditions the convective boundary layer can be significantly higher over the Alps (i.e., around 4 km asl) than over the surrounding lowlands. Subsequent advection may finally result in the export of reactive nitrogen reservoir compounds to the free troposphere and hence influence global atmospheric chemistry.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Separate determination of PM10 emission factors of road traffic for tailpipe emissions and emissions from abrasion and resuspension processes(Inderscience, 28.10.2004) Gehrig, Robert; Hill, Matz; Buchmann, Brigitte; Imhof, David; Weingartner, Ernest; Baltensperger, UrsLittle is known about the relevance of mechanically produced particles of road traffic from abra-sion and resuspension processes in relation to the exhaust pipe particles. In this paper, emis-sion factors of PM10 and PM1 for light and heavy-duty vehicles were derived for different repre-sentative traffic regimes from concentration differences of particles and nitrogen oxides (NOₓ) in ambient air upwind and downwind of busy roads, or alternatively of kerbsides and nearby back-ground sites. Hereby, PM1 was interpreted as direct exhaust emissions and PM10-PM1 as me-chanically produced emissions from abrasion and resuspension processes. The results show that abrasion and resuspension processes represent a significant part of the total primary PM10 emissions of road traffic. At sites with relatively undisturbed traffic flow they are in the same range as the exhaust pipe emissions. At sites with disturbed traffic flow due to traffic lights, emissions from abrasion/resuspension are even higher than those from the exhaust pipes.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Contribution of railway traffic to local PM10 concentrations in Switzerland(Elsevier, 02/2007) Gehrig, Robert; Hill, Matz; Lienemann, Peter; Zwicky, Christoph N.; Bukowiecki, Nicolas; Weingartner, Ernest; Baltensperger, Urs; Buchmann, BrigitteField measurement campaigns of PM10 and its elemental composition (daily sampling on filters) covering different seasons were performed at two sites near the busiest railway station of Switzerland in Zurich (at a distance of 10 m from the tracks) and at a site near a very busy railway line with more than 700 trains per day. At this latter site parallel samples were taken at 10, 36 and 120 m distances from the tracks with the aim to study the distance dependence of the railway induced PM10 concentrations. To distinguish the relatively small railway emissions from the regional background (typically 20–25 μg m−3), simultaneous samples were also taken at an urban background site in Zurich. The differences in PM10 and elemental concentrations between the railway exposed sites and the background site were allocated to the railway contribution. Small, however, measurable PM10 concentration differences were found at all sites. The elemental composition of these differences revealed iron as the only quantitatively important constituent. As a long-term average it amounted to approximately 1 μg m−3 Fe at a distance of 10 m from the tracks at all three sites. Assuming that iron was at least partly oxidised (e.g. in the form of Fe2O3) the contribution can amount up to 1.5 μg m−3. Emissions of copper, manganese and chromium from trains were also clearly identified. However, compared to iron these, elements were emitted in very low quantities. No significant contribution from rock material (calcium, aluminium, magnesium, sodium) was observed as might have been expected from erosion, abrasion and resuspension from the gravel below the tracks. Particle emissions from diesel exhaust were not considered as trains in Switzerland are operated nearly exclusively by electric locomotives. The railway, induced contribution to ambient PM10 decreased rapidly with increasing distance from the tracks. At a distance of 120 m this contribution dropped to only 25% of the contribution observed at 10 m distance.01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Real-world emission factors of fine and ultrafine aerosol particles for different traffic situations in Switzerland(American Chemical Society, 30.09.2005) Imhof, David; Weingartner, Ernest; Ordóñez, Carlos; Gehrig, Robert; Hill, Matz; Buchmann, Brigitte; Baltensperger, Urs01A - Beitrag in wissenschaftlicher ZeitschriftPublikation Iron, manganese and copper emitted by cargo and passenger trains in Zürich (Switzerland). Size-segregated mass concentrations in ambient air(Elsevier, 02/2007) Bukowiecki, Nicolas; Gehrig, Robert; Hill, Matthias; Lienemann, Peter; Zwicky, Christoph N.; Buchmann, Brigitte; Weingartner, Ernest; Baltensperger, UrsParticle emissions caused by railway traffic have hardly been investigated in the past, due to their obviously minor influence on air quality compared to automotive traffic. In this study, emissions related to particle abrasion from wheels and tracks were investigated next to a busy railway line in Zürich (Switzerland), where trains run nearly exclusively with electrical locomotives. Hourly size-segregated aerosol samples (0.1–1, 1–2.5 and 2.5–10 μm) were collected with a rotating drum impactor (RDI) and subsequently analyzed by synchrotron radiation X-ray fluorescence spectrometry (SR-XRF). In this way, hourly elemental mass concentrations were obtained for chromium, manganese, iron and copper, which are the elements most relevant for railway abrasion. Additionally, daily aerosol filters were collected at the same site as well as at a background site for subsequent analysis by gravimetry and wavelength dispersive XRF (WD-XRF). Railway related ambient air concentrations of iron and manganese were calculated for the coarse (2.5–10 μm) and fine (<2.5 μm) particle fraction by means of a Mn/Fe ratio investigation. The comparison to train type and frequency data showed that 75% and 60% of the iron and manganese mass concentrations related to cargo and passenger trains, respectively, were found in the coarse mode. The railway related iron mass concentration normalized by the train frequency ranges between 10 and 100 ng mˉ³ h iron in 10 m distance to the tracks, depending on train type. It is estimated that the personal exposure next to a busy railway line above ground is more than a magnitude lower than inside a subway station.01A - Beitrag in wissenschaftlicher Zeitschrift